//#define LOCAL

#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx,avx2,fma")
using namespace std;
typedef long long ll;
#define MAX 1557557
#define MAXS 19
#define ln '\n'

#ifdef LOCAL
#define DEBUG(a) cout<<a
#else
#define DEBUG(a) 1557
#endif

int C[MAX];
int T[MAX];
ll TS[MAX];
int D[MAX];
int N, M, K, P;
int L[MAX];
int R[MAX];
int smx[MAX];
int nxt[MAX];
int sp[MAX][MAXS];
int ban[MAX];
int pv[MAX];
int ne[MAX];
int ichk[MAX];
int psum[MAX];
inline int dis(int l, int r) {
	if (l <= r) return r - l;
	else return r + N - l;
}
bool chk(ll m) {
	DEBUG(m << ln);
	int i, j;
	for (i = 1; i <= K; i++) {
		int loc = D[i] + N;
		int ind1, ind2;
		ind1 = lower_bound(TS + 1, TS + N * 3 + 1, TS[loc - 1] - m) - TS + 1;
		ind2 = upper_bound(TS + 1, TS + N * 3 + 1, TS[loc] + m) - TS - 1;
		L[i] = (ind1 - 1) % N + 1;
		R[i] = (ind2 - 1) % N + 1;
		if (dis(L[i], D[i]) + dis(D[i], R[i]) >= N - 1) {
			ichk[i] = 1;
		}
		else {
			ichk[i] = 0;
			L[i] = ne[L[i]];
			R[i] = pv[R[i]];
		}
	}
	for (i = 1; i <= N * 2 + 1; i++) smx[i] = N * 3;
	for (i = 1; i <= K; i++) {
		if (ichk[i]) continue;
		int l, r;
		l = L[i];
		r = R[i];
		if (l > r) r += N;
		smx[L[i] - 1] = min(smx[L[i] - 1], r);
		smx[L[i] - 1 + N] = min(smx[L[i] - 1 + N], r + N);
		//DEBUG(L[i]<<' '<<R[i]<<ln);
	}
	for (i = 1; i <= K; i++) {
		if (L[i] <= R[i]) psum[L[i]]++, psum[R[i] + 1]--;
		else {
			psum[L[i]]++;
			psum[1]++;
			psum[R[i] + 1]--;
		}
	}
	for (i = 1; i <= N; i++) psum[i] += psum[i - 1];
	int chk = 0;
	for (i = 1; i <= N; i++) if (psum[i] == K) chk = 1;
	for (i = 1; i <= N; i++) psum[i] = 0;
	if (chk) return true;
	for (i = N * 2; i >= 0; i--) smx[i] = min(smx[i], smx[i + 1]);
	for (i = 1; i <= N; i++) {
		nxt[i] = sp[i][0] = (smx[i] - 1) % N + 1;
		if (sp[i][0] < i) sp[i][0] = N + 1;
	}
	sp[N + 1][0] = N + 1;
	for (j = 1; j < MAXS; j++) for (i = 1; i <= N + 1; i++) sp[i][j] = sp[sp[i][j - 1]][j - 1];
	for (i = 1; i <= N; i++) {
		if (ban[i]) continue;
		int v = i;
		int sum = 0;
		for (j = MAXS - 1; j >= 0; j--) if (sp[v][j] != N + 1) sum += 1 << j, v = sp[v][j];
		sum++;
		v = nxt[v];
		for (j = MAXS - 1; j >= 0; j--) if (sp[v][j] < i) sum += 1 << j, v = sp[v][j];
		sum++;
		if (sum <= P) return true;
	}
	return false;
}
signed main() {
	ios::sync_with_stdio(false), cin.tie(0);
	cin >> N >> M >> K >> P;
	int i;
	ll l, r;
	l = -1;
	r = N;
	for (i = 1; i <= M; i++) cin >> C[i] >> T[i], r += T[i], ban[C[i]] = 1, ban[C[i] + N] = 1;
	for (i = 1; i <= N * 2; i++) {
		if (ban[i]) pv[i] = pv[i - 1];
		else pv[i] = i;
	}
	for (i = N * 2; i >= 1; i--) {
		if (ban[i]) ne[i] = ne[i + 1];
		else ne[i] = i;
	}
	for (i = 1; i <= N * 2; i++) {
		if (!ne[i]) ne[i] = ne[i + N];
		if (!pv[i]) pv[i] = pv[i + N];
		ne[i]--;
		pv[i]--;
		ne[i] %= N;
		pv[i] %= N;
		ne[i]++;
		pv[i]++;
	}
	for (i = 1; i <= K; i++) cin >> D[i];
	for (i = 1; i <= M; i++) TS[C[i]] = TS[C[i] + N] = TS[C[i] + N * 2] = T[i];
	for (i = 1; i <= N * 3; i++) TS[i] += TS[i - 1];
	for (i = 1; i <= N * 3; i++) TS[i] += i;
	while (r - l > 1) {
		ll m = l + r >> 1;
		if (chk(m)) r = m;
		else l = m;
	}
	cout << r;
}